1. Field of the Invention
The invention relates to a rotor of an electric machine, in particular a motor-generator set for pumped storage units, having a rotor body which is arranged on a hub, secured in the axial direction and in the circumferential direction, is constructed from laminated metal sheets and is held together by axially extending clamping bolts, having slots on the outer circumference of the rotor body into which a rotor winding is inserted and held there against the effect of centrifugal force, the winding ends, which emerge axially from the rotor body and form the winding overhang, being secured against the effect of centrifugal force by supporting means having a support ring which is at the same time a thrust plate for the rotor body.
The invention proceeds in this case from a prior art such as, for example, from the book by Wiedemann/Kellenberger "Konstruktion elektrischer Maschinen" ["Designing electric machines"], Springer-Verlag Berlin, Heidelberg, N.Y. 1967, pages 377 to 380, in particular FIG. 375 on page 378.
2. Discussion of Background
For operating reasons, (optimum efficiency, load regulation in pumping operation, power system stability), there is a growing need for variable-speed motor-generator sets, principally for pumped storage units. For reasons of cost, such machines are mostly designed as a double-feed slipring rotor asynchronous machine.
In the case of such machines, the rotor and, in particular there, its rotor winding overhang, are exposed to extreme mechanical and thermal loads. In asynchronous machines, the winding overhangs are usually supported against centrifugal forces by means of bandages made from pretensioned steel wire in combination with a solid single-piece steel ring which is at the same time a thrust ring for the laminated rotor (compare loc. cit., FIG. 375a on page 378). The limits of this design are set by the expensive installations aids and the transport dimensions and by the weight limitation of the rotor. In the case of rotors for hydroelectric machines of large dimensions, it must be possible to form the assembly directly on an installation site in the power station. Moreover, large solid steel rings impair the throughflow of the winding over-hang and thus the cooling thereof.